By the end of next month, Windows 7 and Windows 8.1 users can upgrade to Windows 10 for free or buy a new PC with the new OS pre-installed.

The initial OS release will be limited to PCs and tablets. A Windows 10 upgrade for Windows Phone 8.1 devices will vary by phone makers and carriers.

Starting today, those on Windows 7 and Windows 8.1 will be able to reserve an upgrade via a prompt that should appear in the PC's taskbar. Click "Reserve your free upgrade" when it appears, add an email for confirmation, and you're all set. When it's ready, the upgrade will require 3GB of space.

Those who pick up a Windows 8.1 device before the end of July, meanwhile, can also take advantage of the gratis upgrade.

"With Windows 10, we start delivering on our vision of more personal computing," Terry Myerson, Microsoft's executive vice president of operating systems, said in an announcement.

Designed to run on Redmond's "broadest device family ever," Windows 10 is compatible with Microsoft's PCs, tablets, phones, Internet of Things, Surface Hub, Xbox One, and HoloLens—"all working together to empower you to do great things," Myerson said.

This release marks the return of Microsoft's Start menu, and promises faster overall speed with a quick startup and resume. Windows 10 is also, as the tech giant boasted, "the most secure platform ever."

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On July 29, users can start playing around with functions like Windows 10 Continuum to transition between laptop and tablet, and Windows Hello for a personalized greeting and no-password login.

And while Redmond has ditched its regular Patch Tuesday program, and has said that Windows 10 is the last major version of its operating system, the company promised "new innovations" over time. "Like Windows 10 itself, these updates will be free for the supported lifetime of your device," Myerson said.

Stephanie began as a PCMag reporter in May 2012. She moved to New York City from Frederick, Md., where she worked for four years as a multimedia reporter at the second-largest daily newspaper in Maryland. She interned at Baltimore magazine and graduated from Indiana University of Pennsylvania (in the town of Indiana, in the state of Pennsylvania) with a degree in journalism and mass communications.
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